Global Positioning System (GPS) is a satellite based navigation system that provides positioning, navigation, and timing services to worldwide users on a continuous basis. GPS is made up of three parts: orbiting satellites, control and monitoring stations, and GPS receivers. A GPS receiver obtains signals from at least two GPS satellites to calculate three-dimensional location (latitude, longitude, and altitude) plus the time.
GPS is becoming more popular. GPS receivers designed to be mounted in cars and boats are common. In addition to such dedicated GPS receivers, GPS is becoming available for mobile devices which have the capability of receiving GPS signals and calculating the location data.